Twining or prostrate perennial herb. Flowers in 1-several-flowered bracteate cymes, borne on axillary peduncles. Bracteoles distant from the calyx. Sepals 5; outer 3 larger, accrescent in fruit; inner 2 smaller. Corolla usually yellow (rarely white), usually with a dark centre. Style 1; stigmas 2, ovate-oblong. Capsule with 2-4 seeds.